This section provides background information related to the present disclosure which is not necessarily prior art.
EP-A-0 794 378 discloses a fitting for coupling to at least one pipe, comprising:                a sleeve for receiving the pipe;        at least one sealing member to provide a seal between the sleeve and the pipe;        a pressure member for applying a pressure to the sleeve and to the pipe;        gripper teeth provided on the pressure member and arranged to act on the pipe; and        actuation means for exerting a pressure to the pressure member comprising a pressure ring acting on the pressure member through adjoining slanting contacting surfaces of said pressure ring and pressure member respectively.        
In the fitting of EP-A-0 794 378 the sealing member is arranged between the pressure member and the pipe and between the pressure member and the sleeve in order to provide the required seal between the sleeve and the pipe.
A fitting according to the preamble of the main claim is further known from WO2011/120669.
During installation of the fitting the actuation means of the fitting are arranged so as to have the pressure member apply a pressure capable to withstand for a stand time of not less than 50 years axial forces that may act on the pipe which is received in the sleeve; to provide sufficient pressure both on the part of the sealing member positioned between the pressure member and the pipe and on the part of the sealing member positioned between the pressure member and the sleeve; and to compensate for relaxation of the material of the fitting that may occur during said fifty-year stand time. The pressures that are thus applied to the sealing member, in particular on the part of the sealing member between the pressure member and the sleeve are at such a high level that the sealing member, usually rubber, is overstressed in particular when the pipe diameter is larger than 300 mm. It is particularly with diameters larger than 300 mm that the required pretension on the part of the sealing member between the pressure member and the sleeve becomes too high for the rubber of the sealing member to survive and maintain its long-term physical properties.